The present disclosure relates to a vehicle air conditioner mounted on a vehicle.
Conventionally, e.g., air conditioners each including a heat pump device have been known as air conditioners mounted on hybrid vehicles, electric vehicles, etc. These heat pump devices for vehicles are each configured such that an electric compressor, an outdoor heat exchanger disposed outside a vehicle compartment, an expansion valve, and an indoor heat exchanger disposed inside the vehicle compartment are connected together in this order through refrigerant pipes (see, e.g., Japanese Unexamined Patent Publication No. 2011-005983).
When the heat pump device is in an air-heating operation mode, refrigerant flows such that the indoor heat exchanger serves as a radiator and that the outdoor heat exchanger serves as a heat absorber. When the heat pump device is in an air-cooling operation mode, refrigerant flows such that the indoor heat exchanger serves as a heat absorber and that the outdoor heat exchanger serves as a radiator.
In Japanese Unexamined Patent Publication No. 2011-005983, the flow direction of refrigerant flowing through the outdoor heat exchanger in the air-heating operation mode is opposite to the flow direction of refrigerant flowing through the outdoor heat exchanger in the air-cooling operation mode.
For example, a vehicle air conditioner of Japanese Unexamined Patent Publication No. 2011-255735 includes an upstream indoor heat exchanger disposed on an upstream side in the flow direction of air, and a downstream indoor heat exchanger disposed on a downstream side in the flow direction of air. Moreover, a four-way valve is provided at a refrigerant pipe, and switches to switch operation modes such as an air-heating operation mode and an air-cooling operation mode.
The downstream indoor heat exchanger serves as a radiator in both of the air-heating operation mode and the air-cooling operation mode. On the other hand, the upstream indoor heat exchanger serves as a radiator in the air-heating operation mode, and serves as a heat absorber in the air-cooling operation mode.
As another example, a vehicle air conditioner of Japanese Unexamined Patent Publication No. H09-240266 includes, as indoor heat exchangers, an upstream indoor heat exchanger disposed on an upstream side in the flow direction of air, and a downstream indoor heat exchanger disposed on a downstream side in the flow direction of air. The downstream indoor heat exchanger serves as a radiator in both of an air-heating operation mode and an air-cooling operation mode. On the other hand, the upstream indoor heat exchanger serves as a heat absorber in both of the air-heating operation mode and the air-cooling operation mode.
Since strong air-heating is required for the air-heating operation mode particularly under low outdoor air temperature, there is a possibility that an air-heating capacity becomes insufficient when the upstream indoor heat exchanger serves as the heat absorber in the air-heating operation mode as described in Japanese Unexamined Patent Publication No. H09-240266.
In view of the foregoing, the upstream indoor heat exchanger may serve as a radiator in the air-heating operation mode as described in, e.g., Japanese Unexamined Patent Publication No. 2011-255735. That is, the refrigerant pipes are connected such that refrigerant discharged from the compressor flows through the upstream indoor heat exchanger after flowing through the downstream indoor heat exchanger. This allows air heated by the upstream indoor heat exchanger to be re-heated in the downstream indoor heat exchanger, and therefore there is an advantage that the air-heating capacity can be improved. On the other hand, since depressurized refrigerant is, in the air-cooling operation mode, supplied to the upstream indoor heat exchanger to cause the upstream indoor heat exchanger to serve as the heat absorber, air-cooling can be also performed.